(Ames, IA) -- Mosquito populations are rising after years of drought. Iowa State University entomologist Ryan Smith credits regular rains and flooding for the booming populations. He says Polk and Black Hawk counties have had the highest numbers.
Iowa has more 50 types of mosquitoes. Some carry disease. Others don’t. Mosquitoes most often prey on birds and other wildlife or even livestock, with females sucking blood needed to produce eggs. When mosquitoes bite humans, they sometimes transmit diseases in the process.
The most common mosquito, Aedes vexans, is not a carrier of human disease. Species that pose more risks to humans include types of Aedes and Culex mosquitoes that can carry West Nile virus or other mosquito-borne diseases. WNV can be deadly to a small percentage of those exposed, especially the elderly or those with compromised immune systems. Most people who contract WNV will experience mild or no symptoms, so its occurrence is likely underreported, according to Smith.
Iowa State reports so this year, 19 mosquito samples have tested positive for WNV, and one human case reported (in Harrison County). In 2023, 96 mosquito samples tested positive for WNV, and 17 human cases were identified.
“This year, we’re finding relatively high numbers of Culex tarsalis, typically found in agricultural and irrigated areas. Their presence can really be a problem, especially in northwest Iowa, a known hot spot for this type of WNV-carrying mosquito,” Smith said.